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{"created":"2022-01-31T12:52:53.456780+00:00","id":"lit28742","links":{},"metadata":{"alternative":"Studies from the Yale Psychological Laboratory","contributors":[{"name":"Scripture, Edward W.","role":"author"}],"detailsRefDisplay":"Studies from the Yale Psychological Laboratory 5: 88-89","fulltext":[{"file":"p0088.txt","language":"en","ocr_en":"CEREBRAL LIGHT.1\nBY\nE. W. SCRirTURE.\nIn darkness or with closed eyes we can always see irregular forms of light in our visual field. These forms are of various kinds, series of waves, successive rings that spread and break, etc. In addition to these definite figures there is always more or less definite irregular illumination over the whole field. These phenomena are generally called \u201c the retinal light \u201d or the \u201c Eigenlicht of the retina.\u201d They are usually supposed to arise from chemical changes going on in the retina. I wish to record some observations that apparently prove them to be cerebral and not retinal processes.\n1.\tWith closed eyes there is only one illuminated field, not two, as there should be from the two retinas if the light were retinal. Two retinal figures might appear as one under the conditions : (a) of suppression of one field, which is not the case here, because it is impossible to keep one field suppressed for many minutes, whereas I have watched the retinal figures in uninterrupted continuance for a long time ; (/>) of perfect identity of form, which is hardly a possible supposition in the case of these irregular, volatile, chemical phenomena ; (f) of sufficiently similar construction for union by stereoscopic vision, which also is not the case, as there is no relief-effect in the picture.\n2.\tThe figures do not change in position when the eye is moved. They are localized in front and remain in the same place, even if the eyes are directed to one side. I find, however, that if the eyes are turned to a new position and kept there, the central figure (a spreading violet circle with a phosphorescent rim) will soon afterwards follow the movement ; there is thus a tendency for this figure to occupy the spot of sharpest vision.\n3.\tThe figures do not change in location when the eyes are displaced. When the eyes are looking at some definite object, e. g., this page, a pressure of the finger on one of them will cause the page apparently to move. This is true whether the other eye is open or closed. Likewise, if an after-image is obtained, it will move upon pressure of the eyeball. The pressure displaces the eyeball and changes the projection of the re-\n1 This account was first published in Science, 1S97 N. S. VI 138.\n88","page":88},{"file":"p0089.txt","language":"en","ocr_en":"89\nCerebral light.\ntinal picture. This displacement does not occur with \u201c retinal light.\u201d I have repeatedly observed these figures and have manipulated the eyeballs ; I have found that they are not in the slightest degree affected by the manipulations. In order to avoid all possibility of errors of observation, I have made the experiments in a series alternately with eyes open and eyes closed. With the eyes open I observed a dimly illuminated window; with them closed I saw the \u201cretinal\u201d figures. The former always followed the displacements, the latter never.\nThese observations are, I believe, sufficient to establish the proposition (which I have not seen elsewhere) that the phenomena of vision usually known as \u201cretinal light\u201d and \u201cretinal figures\u201d are not originated in the retina, but in the brain. They should, therefore, be termed \u201ccerebral light\u201d and \u201ccerebral figures.\u201d\nThe following hypothesis seems also justified. The cerebral light is located in those higher centers of the brain which are connected with visual memories and imaginations. While watching the cerebral figures I find that my visual memories or phantastic figures appear in the midst of the cerebral light and frequently cannot be distinguished from them. The close connection of these cerebral figures with the contents of dreams has been repeatedly noticed by Johannes Mueller and a series of later observers. There is also the possibility that the hallucinatory visions produced by hashish, mescal and other drugs may be simply modifications of this cerebral light.","page":89}],"identifier":"lit28742","issued":"1897","language":"en","pages":"88-89","startpages":"88","title":"Cerebral light","type":"Journal Article","volume":"5"},"revision":0,"updated":"2022-01-31T12:52:53.456785+00:00"}